Glossary of Constructed Wetlands Terminology
Absorb (absorption)
The passing of nutrient material into the body of a plant or animal.
Acidogenic leachate
A leachate which is converted by anaerobic microbial activity to carbon dioxide and organic fatty acids.
Activated sludge
A method of biological wastewater treatment involving aeration with flocculating microbial biomass.
Adsorb(adsorption)
The collection of nutrient material on the surface of the plant or animal.
Aerobic
Requiring atmospheric oxygen.
Algae
One of many-celled microscopic aquatic plants.
Ammonification
The first stage of nitrogen transformation by reduction to ammoniacal nitrogen.
Anearobic
A condition in which no oxygen is available as free oxygen, nitrite or nitrate.
Anoxic
Deficient in dissolved oxygen (not containing dissolved oxygen but where reduction of nitrate or nitrite may occur).
Aspect ratio
Length to width ratio.
Autotrophic
Able to derive energy from inorganic reactions, e.g. nitrifying bacteria.
Batters
The inclined sides of a constructed wetland from the surface of the bed to the level of the surrounding soil.
Biochemical oxygen demand(BOD)
The amount of dissolved oxygen consumed by the degradation of organic matter by bacteria in water in the dark, usually over a period of 5 days at 20°C.
Biofilm
The microscopic growth of organisms which forms as a slime over stones, plants or some other support usually in aquatic environments.
Biological filter
A bed of inert material; sewage trickles through the media and is treated through the action of bacteria and other microorganisms; also known as a conventional,trickling or percolating filter.
Biomass
The mass of animals and plants within a habitat measured at a given time.
Biota
Community of living organisms.
Blinding
Blocking or clogging with small particles or debris.
Broadcast
Scatter freely.
Cascade
Fall of water by gravity from a high to low level.
Chemical oxygen demand (COD)
The amount of oxygen consumed by chemical oxidation.
Consent Standard
Licence to discharge wastewater at or better than a standard set by a regulatory authority; UK Water Companies usually have to comply with BOD/SS/amm-N standards, and possibly with additional phosphorus, total nitrogen and bacteria standards.
Constructed wetland
Artificial wetland engineered to achieve biological and physicochemical improvement in the environment.
Conventional filter
See biological filter.
Denitrification
The reduction of nitrite and nitrate to nitrogen gas by bacteria under anoxic conditions.
Discharge consent
Consent issued by the Environment Agency under Schedule 10 of Water Resources act 1991.
Emergent macrophytes
Aquatic plants rooted in the support medium with much of their green parts above the surface of the water.
Eutrophication
Enrichment of the aquatic environment with nutrients resulting in increased primary production.
Evapotranspiration
Loss of water vapour from the leaves of green plants during photosynthesis.
Facultative
Capable of living aerobically or anaerobically.
Freeboard
Vertical distance between the maximum water level in a container and the top of the side walls of the container.
Grey water
Water from sinks, baths, showers and kitchens.
Heavy metals
Metalliferous elements and their derivatives including zinc, lead, copper, iron, mercury, cadmium, cobalt, manganese and nickel.
Hydraulic conductivity
The ability to support medium to conduct fluid through the interstices between particles which make up the medium.
Hydroponics
The cultivation of plants in a liquid film of nutrients.
Indicator bacteria
Micro-organisms used to indicate the presence of faecal contamination.
Invertebrate
Animal without a backbone.
Ionic exchange
Movement of chemical ions between sites.
Litter
A layer of dead vegetation which serves as an important site for micro-organisms.
Macrophytes
Green plants.
Macroscopic
Visible with the naked eye.
Malodorous
Evil-smelling, nauseous (offensive to smell).
Marl
A mixture of clay and carbonate of lime.
Medium
Soil, gravel or other material used in a constructed wetland in which to grow plants and support micro-organisms; also known as support matrix.
Methanogenic leachate
A leachate which is converted by anaerobic methanogenic bacteria to produce methane.
Micro-organism
An organism that is not visible with the naked eye.
Nitrification
The oxidation of ammoniacal nitrogen to nitrite and nitrate by autotrophic bacteria under aerobic conditions.
Nitrogen fixation
Conversion of nitrogen gas into nitrogenous compounds.
Nutrient
A substance that supports growth.
Organic loading
The strength of wastewater measured by its amount of organic matter able to be consumed by biochemical processes.
Pathogen
A disease-producing organism.
Percolating filter
See biological filter.
Permeable
Allowing movement of liquids and gases.
pH
Scale based on hydrogen ion concentration and ranging from highly acid (0) to highly alkaline (14)
Photosynthesis
Process by which the energy of sunlight is trapped by green pigment in plants, and is used to build up plant tissue from carbon dioxide and water.
Plug flow
Theoretical movement of fluid particles which pass through a compartment without dispersion and are discharged in the same sequence and at the same concentration in which they entered.
Polyculture
An integrated culture of aquatic animals and plants that co-exist so that their combined effect is to improve water quality.
Population equivalent
Amount of degradable matter (expressed in terms of BOD or of other significant properties) or volume of wastewater produced per capita (1 pe < 150 l.d-1 < 0.15m3.d-1).
Precipitation
The process by which chemicals move out of solution to be deposited in soild form; also rain, snow , sleet or hail.
Primary production
Incorporation of carbon dioxide into organic matter by photosynthetic organisms or autotrophic bacteria.
Primary treatment
Physical separation of solids, usually by settlement, before secondary biological sewage treatment.
Productivity
The rate of production of biomass.
Puddled
To knead into an impervious layer.
Rhizomes
Below ground stem of macrophytes.
Root zone
The area around the growing tips of the roots of a plant.
Roughing filter
A biological filter which is operated at a high loading rate to achieve partial pre-treatment of wastewater.
Screening zone
A zone which provides a screen to protect reeds from storms of wind and rain.
Secondary treatment
First biological stage of treatment for sewage.
Sewer dikes
Trenches or ditches into which sewage flows and infiltrates into the surrounding soil for purification by micro-organisms growing in the soil.
Substrate
Substances acted upon by an enzyme or a surface upon which a micro-organism lives and from which it may derive nutrients.
Support medium
Soil, gravel or other material used as the support matrix within the constructed wetland.
Suspended solids (SS)
Dry weight per volume of matter in a sample retained by a filter.
Tertiary treatment
Treatment following the biological stage of treatment for sewage, which may incorporate removal of nitrate and removal of surplus suspended solids.
Total solids (TS)
Material remaining in a sample when all the water has been evaporated.
Trickling filter
See Biological filter.
